The ACS Infininte Minutes plan allowed residential customers unlimited interstate calling for a flat rate of $20 a month. But last month, after losing money, ACS capped the plan at 600 minutes a month for existing customers, in part because some people were using Infinite Minutes for business calls.

Adelman alleges ACS knew the plan wouldn't work but used it to lure customers. ACS spokesman Tom Jensen called the complaint ''a typical nuisance suit'' and said most customers understand why the company cannot continue the plan.